# Collision of two electron beams as an experimental test of the Standard Model? [closed]

I understand from this link that no experiments that collide two electron beams (cf. electron-position beams) at high energy were ever done. Assuming the standard model (SM), such a collision should generate electron-positron pairs.

Should this experiment - a collision of two electron beams to detect the generation of electron-positron pairs - be done as a test of the SM?

## closed as too broad by Michael Seifert, Jon Custer, Buzz, ZeroTheHero, M. EnnsFeb 10 at 13:39

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• At SLAC, 50GeV electrons go flying into a beam dump (with lots of electrons) all the time. And, how is this really different (in the SM context) from electron-positron scattering, which is also routinely done? – Jon Custer Feb 8 at 15:40
• @Jon Custer The difference from electron-positron scattering is initial absence of positrons in the case of two electron beams. Then if we will see electron-positron pairs it will be clear answer. – VYT Feb 8 at 16:50

Quite contrary to the answer mentioned in the link you provided, there were electron electron collision experiments. In fact, they were the first collider experiments that have been conducted.

So, electron electron collisions are also called Moller scattering which is well described quantitatively by the feynman rules for Quantum Electro Dynamics.

First, there is VEP-1 collider in Novosibirsk, Russia. It is a collider with an energy of $$2*160 \,\mathrm{MeV}$$. It reached a luminosity of $$4*10^{28} \,\mathrm{cm^{-2}s^{-1}}$$. The experimental studies on scattering of electrons were conducted and the following reactions were observed

$$e^{-} e^{-} \rightarrow e^{-} e^{-} \gamma$$

$$e^{-} e^{-} \rightarrow e^{-} e^{-} 2\gamma \tag{Double bremstrahlung}$$

So, the first reaction can be seen as a pair annihilation producing a photon. But, most probably it was from bremsstrahlung of either the initial or final states.

Secondly, there is also a collider in the US which is the Princeton-Stanford Experiment Collider. It was the most powerful electron accelerator during it's time. It is a collider with an energy of $$2*500 \,\mathrm{MeV}$$. It reached a luminosity of $$2*10^{28} \,\mathrm{cm^{-2}s^{-1}}$$. It has conducted several tests for QED.

QED is very well tested and understood. So, according to me we do not require a electron electron collider even at high energies today. I am more excited to see a Linear Collider of electron positron of higher energies or a muon anti-muon collider.

Also, if you would like to read about these colliders here is the link: https://arxiv.org/abs/1307.3116

• I know about VEP-1 collider in Novosibirsk, Russia, this is why I have written "at high energy". From the VEP-1 collider results we can say that electron-positron pairs have not been detected, but it can be because low energy of electron beams. Do you know which results were in Princeton-Stanford Experiment Collider ? – VYT Feb 8 at 17:12
• If you have access to the paper about Princeton-Stanford Experiment Collider results journals.aps.org/prl/abstract/10.1103/PhysRevLett.16.1127 can you look if the paper reports about electron-positron pairs detection ? – VYT Feb 8 at 17:32
• I've taken the liberty of changing your markup to conform to the usual rule that units are typeset in upright text and set off by a thin space. And set your reactions as display equations while I was in there. – dmckee Feb 8 at 18:18
• @VYT Thanks for sharing, I have access to the paper. So, in the paper they compared the observed angular distribution to the one expected from Moller scattering formula which includes feynman regularization and radiative corrections in it. They did not mention anything about observing electron-positron pairs. – Invariance Feb 8 at 20:07
• @Invariance Thank you for the info! So, we can say nothing conforming about generation of electron-positron pairs from both the VEP1 and the Princeton-Stanford Experiment Collider. Should this control experiment be done, what do you think ? – VYT Feb 8 at 21:39